Method of and apparatus for condensing



F. R. KEMMER Y 29H4., METHOD OF AN) APPARATUS FOR CONDENSING Filed July 8, 1933 July 4, 1939.

ATTORNEY.

'l5 ly cooled from, a

Patented July 4, `1939 'v ME'rnon a corporation of or AND APPARATUS Fon coNnENsiNe Frank R. Kemmer, Larchmont, N.

to Magnesium Products, Inc., Wilmington, Del.,

Delaware Y., assignoranimation July s, lass, serai No. 679,498 r emma' (ci. vs -s1) This invention relates 'to l magnesium vapors, more particularly to a method of and an apparatus for condensing such vapors when mixed with other` gases so as to prevent' s chemical reaction with the magnesium.

It is now recognized that mixtures of magnesium vapors andCO. for example, obtained by the reduction of a magnesium oxide ore and carbonaceous material, for example, are unstable in that at certain temperatures there is a reaction between the magnesium and the C to produce esium oxide, thus destroying the eillciency of the operation. It has been recognized that if a mixture oi' magnesium vapors and CO israpidtemperature above such reversion point to a relatively low temperature this reversion oi magnesium to a magnesium compound may bealmost entirely prevented.

This application is a continuation in part of 20 my application Ser. No. 542,104, led June 4r,

1931, in which I have described the rapid .-cooling of the mixture of Mg vapor and C0, jin' a water-cooled condenser, in order to prevent eversion reactions from taking place which would tend to reoxidize the magnesium.

also in my copending application Serial No. 664,932, iiled April 7, 1933, and entitled "Method, of and apparatus for condensing magnesium" I have described a method 'of quickly cooling and gg condensing suchmagnesium vapors by causing the same to contact witha tllni` of an oil which cools, condenses and protects the magnesium from undesirable reactions.

'While such a process is perfectly feasible and 35 .has been operated with success, I find that certain disadvantages are inherent therein. 'The resultant product is a mixture of iinelydivided magnesium and oil, making it necessary to remove most of the oil from the magnesium prior 40 to the next stage of the operation. Thisrequires various types of apparatus such as are well known and which may be used with good results, but they introduce elements of cost in `the equipment, in the, operation thereof and increase the cost of maintenance! The present inventionis intended to provide a method of and an apparatus for condensing such magnesium vapors without the use of'a liquid condensing medium and coolingfrom a high temperature to substantially atmospheric temperatures that no appreciable reaction o1' the magnesium with other constituents of the vapors can take place.

the condensing of metallic state. a very eil'ective condenser but does not serve as without diluting the"` 50 vapors to an undesirable'extent. I'he invention further contemplates such a quick and drastic I have found that the condensation of mag- I nesium vapor from such a mixture to finely divided magnesium 'powder and its preservation in said metallic state 'depends on the very sud#- den and drastic chilling of such mixture from above 1200 C. to a. very'low temperature. The condensation phenomenon is very beautifully exhiblted by placing a, cold iron bar into a stream of the hot mixture of magnesium vapor and carbon monoxide gas for an interval of time so i short that the'bar cannot become appreciably heated and then suddenly withdrawing said bar. The bar on withdrawal is found to be completely covered throughout the length of insertion in the gaseous mixture with nnely divided sona 416v magnesium particles which on coming into the air ignite immediately and ,thev A scintillating f oxidation follows rapidly along the, bar as it continuestp be withdrawn. This experiment shows very strikingly the fact of condensation of the magnesium vapor to its nely divided and solid The cold iron bar has acted as a collector` of the powder in a, commercial or practical way. ,25

The system described herein successfully overcomes the difficulties inherent in other types of water cooled condensers. It consists of a chamber built up of walls which may be Water cooled and in theinterior of which is mounted a wago ter cooled drum (interior coolingl the periphery of which is caused to come practically up to the point of entry into the condenser of the-gaseous mixture of Mg and/or CO and/or other gases. This permits instantaneous condensation of magnesium metal. A scraper is provided to remove the thin film of nely divided solid magnesium particles so that the condensing eciency of the water cooled drum surface is at all times preserved in its high state of eciency By means oi a water cooled screw the iinely divided magnesium powder may. be cooled to room temperature prior to dischargev or below room tempera,-` ture by the use of supplemental brine refrigeration.- V In the accompanying drawing constituting a part hereof land in which like reference charac- `tex-s indicate ylike parts:

The apparatus'generally consists of a.- shell i 66 l or remove from said surface of any suitable material, which may be exposed to the air so that it is air cooled or may be cooled by a water spray or water jacket and an openin shell I is mounted `for rotation on shaft l,

The surface of the drum to the inlet opening 2 and by means not shown. is in close proximity a scraper or other device 6 is arranged usually' drum 3 to scrape 5 any accumulation of deposits of magnesium powder which may at the lower portion of the have formed. The lower portion of the shell is tapered'as shown at 1 to form a trough and a screw conveyor 8 which may or may not be water cooled is inserted therein. This serves as means for removing the' powdered magnesium from the apparatus and in the normal operation thereof such powder has been cooled to about atmospheric temperature before removal.

Connected to or constituting a part of shell I is an additional shell 9 having therein a series of baiiles I0, II, I2 and I3 to causeV the gases coming from shell I to flow in a winding and twisting path, so as to contact with said bailles. The bailles may be cooled artificially as by means of circulating water in a jacket attached to or constituting part of said bailies. As shown, the baiiles are hollow so that the water or other cooling medium may circulate therethrough by means of inlet and exit pipes (not shown) suitably connected thereto. The lower portion I4 of shell 9 is tapered to form a; trough within which is a screw conveyor I5 similar to conveyor 8. Gases'fiowing from shell yil pass through exit opening I6 and then downwardly through pipe I1 into liquid seal arrangement I8. Said liquid seal is provided with a baiiie I9 and liquid up to level 20 which is just short oi' the lower end of baille I9 forming a narrow space 2l for gases to now. An extension 22, as best shown in Figure 2, provides an opening for inspection for iilling and for emptying the seal I8. An exit pipe 23 on the side of baille I9 opposite to pipe I'I allows the removal of the waste gases from the system.

In'the operation of the device a mixture of magnesium vapors and CO, for example, enters opening 2 at a' temperature of approximately 1200"C. or higher and immediately impinges upon the surface 5 of drum 3 which is rotating relatively slowly. By reason of the cooling eilect .of the water within the drum there is a strong chilling of the magnesium vapors to form powder which is cooled to a temperature considerably below 100 C. and ordinarily is in the neighborhood of 30 C. or even less. This forms a thin layer of magnesium powder on the drum 3 and thereby the magnesium is removed from intimate admixture with CO, whereby contact with CO is not detrimental, greatly decreasing any danger of reversion taking place. The powder is carried to the lower side of the drum where scraper 6 removes the same and restores a clean, cool surface for the condensing of magnesium. The powder falls into conveyor S and is thereby removed from the system. The powder may be transferred to a chamber having an inert or reducing atmosphere such as hydrogen. Usually the CO in the system imparts sufficient proteotive gas to prevent access of air but I also contemplate operating the system in the presence of an indierent gas, for example, an inert or reducing atmosphere such as hydrogen, helium or the like which may be introduced into the apparatus by a pipe or the like.

'The gases containing some magnesium which may have escaped condensation on the rotating water cooled drum are carried past the baffles III, II, I2 and IJ where they are further cooled, causing the condensation of additional magneslum powder which may accumulate on the baffles and fall into trough Il or be scraped from the bailles and carried away out of the system by conveyor I5.

The exit gases pass through pipe I1 and through the liquid seal I8 wherethey are scrubbed at the surface 20 of the liquid to re- 'move any magnesium powder carried along by the gas and the spent gases are removed 'from pipe 23.

Although I have described my invention setting forth a single embodiment thereof and indicating the normal operation of the system. it

will be apparent to those skilled in the art that various changes and modifications therein may be made within the scope of the invention. For example, the scraper 6 may be placed in a different position and the drum 3 may be replaced by a stationary cool surface and a cleaning device may be moved over the surface thereof to remove deposits as they accumulate. The baiiles may be removed or a larger number may be used and the liquid seal may be replaced by a bag or other dust collecting apparatus. The baille I8, liquid level 20 and? space 2I act as a pressure regulator for the system, the pressure of which may be varied by varying'the size of the 'space 2|. A pressure regulator may be added to the system to automatically maintain. the system under pressure to any desired degree, so that air cannot enter the system. All of the parts of the condenser may be water cooled. These and other changes may be made in my invention without departing from the principles thereof. My invention is to be broadly construed and to be limited only by the claims appended caused to make contact with'the cooled surface as soon as possible. after they leave the furnace so that they make contact with the chilled surface before there is an opportunity for cooling oi the gases into the range of temperature where the reverse reaction between Mg and CO'takes place to any substantial degree.

What I claimis:

1. Apparatus for condensing magnesium vapors contained in a gaseous medium comprising a. chamber, an opening therein for the introductionof said gas. an artificially cooled surface, means for directing said gas so as to cause it to immediately impinge thereon and means including a circulating uid for maintaining said sur- -face at a sufficiently low temperature so that magnesium vapors are rapidly cooled through the range of temperature in which magnesium is reactive with CO whereby the magnesium is condensed thereon and reaction with other constituents of the gas is substantially prevented, and a pressure regulator in the system.

2. Apparatus for condensing magnesium vapors contained in a gaseous medium including CO resulting from the reduction of magnesium oxide ore'with carbon comprising a device for the generation oi magnesium vapors, a condenser connected thereto, and a pressure regulator situated beyond said condenser and operatively connected to the exit end thereof,v said regulator being adapted to maintain a higher pressure in said condenser than prevails beyond said `regulator.

3. A method which comprises heating an oxide ore of magnesium with a carbonaceous reducing medium to produce a gaseous mixture containing magnesium vapors and CO at a sufficiently l high temperature so that there is substantially no reaction therebetween, leading said mixture to a clean cold surface and causing the same to impinge directly thereon immediately upon leaving the reaction chamber, the cooling effect of said surface acting to reduce the temperature of said mixture suiliciently rapidly to condense said vapors and 'to substantially prevent reaction between magnesium and CO, and continuously moving said surface to present a clean cold portion to said mixture.

4. A method which comprises heating an oxide with a -carbonaceous reducl ing medium to produce a gaseous mixture con-` ore of magnesium taining magnesium vapors and CO at a sufciently high temperature so that there is sub-- stantially no reaction therebetween, leading said mixture to'a clean cold surface and causing the same to impinge directly thereon immediately upon leaving the reaction chamber, the cooling effect of said surface acting to reduce the `temperature of said mixture sufiiciently rapidly to condense said vapors and to substantially prevent reaction between magnesium and C0, continuously moving saidsurface to present a clean cold portion to said mixture and continuously scraping oi the metal adhering to said surface.

5. An apparatus comprising a reaction chamber for the production of a gaseous mixture of magnesium and CO, a condenser, a connection therebetween, a cooled surface in said condenser,

to present cleansurfaces to said mixture and means for continuously scraping condensed metal from said surface.

7. An apparatus comprisinga reaction chamber for the production of a gaseous vmixture of I magnesium andv C0, a condenser, a connection therebetween, a continuously rotating drum having a cooled surface insaid condenser, said connection being so located as to cause said gaseous mixture to impinge directly on said surface, and

to said mixture.

lmeans for continuously presenting clean surfaces p "FRANKR-KEMMER- 

